Safety valve device



IIN-.l 44

July 6, 1954 Q MAY 2,682,890

SAFETY VALVE DEVICE Filed July 27, 1951 IN V EN TOR.

ATTORNEY ,gral pipe-threaded nippleli. Y

Patented July 6, 195.4l

SAFETY VALVE DEVICE Harry C. May, East McKeesport, Pa., assignor toWestinghouse Air Brake Company, Wilmerding, Pa., a corporation ofPennsylvania `Application July 27, 1951, Serial No. 238,796

1 Claim. 1

This invention relates to fluid pressure relief valves and moreparticularly to safety valve devices of the poppet type used in fluidpressure apparatus.

The principal object of this invention is to provide an improved safetyvalve device which is capable of operation without noise resulting frompulsating pounding, or vibration, ofthe valve thereof on its seat.

Other objects and advantages will appear in the following more detaileddescription given in connection with the accompanying drawing,r

wherein:

Fig. 1 is a vertical sectional view of a safety valve device embodyingthe invention;

Fig. 2 is a sectional view taken on the lines 2--2 of Fig. 1; and Y Fig.3 is a sectional View taken on the lines 3-3 of Fig. 1. Y Y

In the embodiment shown, the safety valve device comprising a valvebodyA I, a spring'housing 2,andacap3. L

Provided in the body I Vis a bore 4which may communicate by way ofr apassageway 5 at the outer end of said bore with a reservoir (notshown),1or other uid pressure element or port.

to be vented, in which reservoir or port the body is arranged to bemounted byxmeans of an inte- A cylinder member 'I disposed at the outerend of bore 4 in abuttingengagement with the end wall of the bore hasformed therein a cylinder 8 in which a piston 9 is operably mountedrforrei.'

ciprocation therein. At the right-hand side of piston V9, as viewed inFig. 1, is a chamber I0 which is in constant communication rwith theaforementioned reservoir or fluid pressure element (not shown) by way ofafpassageway YII formed inthe cylinder member 'I and an extension 1athereof which projects through passageway'5 to the mouth thereof. Avalve seat member I2 disposed at the inner end of bore 4 is adapted toabut the cylinder member 'l for the purpose offholding the cylindermember in the position shown. The valve seat member I2 has formed aboutits periphery a groove I3 in which an annular sealing ring I4 is pressedbetween the walls of the groove and the wall of the bore 4. Thiscontact, together with the frictional contact of the periphery of themember I2 with the wall of the bore 4, serves to retain the memberrinthe position in which it is shown in Fig. 1.

Formed in the valve seat member I2 in coaxial aignment with cylinder 8is a through bore I5 having one end open to boreL 4 by Way of a .chamberIBand the other end encircled by a valve seat I'I adapted to be engagedby a disc valve I8 disposed in a chamber I9 which is constantly open toatmosphere through ports 29 in the spring housing 2 which is secured inthe body I by screwthread means 2a;

As shown in the drawing, the valve I8 is en gaged on its under, orinner, side by a piston stem 2 I, formed integral with piston 9, for thepurpose of unseating said valve.

The valve I8 is constantly engaged on its opposite side by a follower 22which is contained in the spring housing 2 and is provided with anintegral wearing button 23 for Contact with said valve. A spring 24 isalso contained in a chamber 25 in housing 2 which at one end engages aspring seat 26 formed in the cap member 3 and at the other end follower22 so as to constantly urge valve I8 toward its seated position asshown. The chamber 25 in housing 2 is constantly open to atmospherethrough ports 2I in cap member 3. t Mounted on` the threaded portion ofthe spring housing 2 inwardly of the cap portion 3 is a jam nut 29whichmay be utilized to lock the cap portion 3 .in a proper adjusted positionfor obtaining theproper compression on'spring 24 and thus the propersetting for the unseating of the valve is, i

vIn operation, when the pressure of fluid in the reservoir, or port tobe vented, and thus in passageway 5 and bore I5 acting over the exposedarea ofthe onevface of valve I8 is sufficient to overcome the opposingpressure on the opposite face of saidvvalve of the spring 24 which hasbeen adjusted tothe desired venting pressure, the valve I8 willbe movedby the preponderance of fluid pressure in bore I5 away from the seatI'I. When the valve I8 is moved away from seat I1 slightly, fluid underpressure will then iiow past the seat into chamber I9, and thencethrough'passage- Y ways 29 to atmosphere. It should be noted that priorto the unseatng of valve I8 the fluid pressures acting on opposite facesof the piston 9 are equal and therefore piston 9 exerts no force ineither direction. However, upon valve I8 being unseated there is alocalized drop in iiuid pressure acting on the left-hand face of piston9, as viewed in Fig. 1 of the drawing, resulting from the ow of fluid tochamber I0 through passageway II.

It should also be ,noted that the area of valve i8 over which iluidpressure acts when the valve is seated is appreciably less than the areaof either face of piston 9 which is subject to fluid pressure.Consequently, immediately after unseating of valve I8, the excess ofpressure acting on the right-hand face of piston 9 through the medium ofstem 2| augments the force acting in a direction for moving the valvefurther away from its seat I'I. Thus a prompt and positive movement ofvalve I8 to its extreme open position is obtained by the action ofreservoir pressure in chamber I on piston 9. With the valve I8 unseatediiuid under pressure in the reservoir will ow to atmosphere throughpassageway 5, bore 4, chamber I6, bore I5, chamber I9 and ports 20.

The valve I8 will be held oil the seat I1 by the preponderance of fluidpressure in chamber I0 acting on the piston 9 until the pressure ofiiuid in the reservoir and thus in passage II and chamber I0 drops to adegree which will permit spring 24 to prevail again and return valve I8to seat I'I. Upon seating of valve I8 the opposing fluid pressures inchambers I9 and i6 acting on piston 9 are again equalized.

It should be noted that the area of valve I8 over which fluid atreservoir pressure acts when the Valve is seated is appreciably lessthan that of the opposite end faces of piston 9 that are subject toopposing uid pressures. Consequently, the reservoir pressure will nowhave to increase to a degree which will exert sumcient force on theenclosed area, or non-atmospheric portion, of valve I8 to again overcomethe force of spring 24, whereupon iiuid in chamber I9 at reservoirpressure will act over the greater area of piston 9 to actuate the valvetoits extreme open position.

From the foregoing it can be seen that I have provided a safety valvedevice which employs novel iiuid pressure means whereby valve AI8thereof is held positively iny either its closed or extreme openposition and undesired pulsating and noise will be eliminated. Moreover,by virtue of passageway II pressure in chamber I0 will always equalthat-,in the reservoir to Vprovide for positive control of closing ofvalve I8 by reservoir pressure instead ofA the lower pressure which willbe present in passage and bore I5 while iluidis being vented throughVsaid passage and past said valve. Still further, the passageway II beingprovided in the extension 1a of 'element I, which extension is withinthe nipplev 6, provides for making both connections (via passageways 5and II) to a reservoir merely by attachment of said nipple.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

A safety valve device comprising two tubular casing portions separablysecured together in coaxial relation, one casing portion comprising atone end a nipple and having an axially extending cylindrical chamberopen at one end tc site end of said chamber with the outer end of saidnipple, the other of said casing portions having an axially extendingpassage therethrough and also having a radially extending passagetherethrough in ysuch position that said one end of said cylindricalchamber in said one casing portion opens into said radially extendingpassage in said other casing portion in the assembled condition of saidcasing portions, an element adapted to be inserted in said cylindricalchamber into contact with said opposite end of said cylindrical chamberprior to assembly of the two casing portions and comprising a tubularextension which extends from said chamber through the said cylindricalpassage to the outer end of said nipple, said element having therein acylindrical chamber open at one end to the cylindrical chamber in saidone casing portion and open at the other end to said tubular extension,a valve seat disc also adapted to be inserted in the said cylindricalchamber of said one casing portion into contact with said element priorto assembly of the casing portions to each other and having sealingengagement with the wall of the last named chamber, said valve seat discand said element being clamped in the said cylindrical chamber of saidone casing portion by said two said casing portions when securedtogether, said valve seat disc having an axially extending passagetherethrough open at one end to the open end of said chamber in saidelement and at the other end to said radially extending passage anddefining with said element a port connecting the passage in said valveseat disc to said cylindrical chamber in said one casing portion, anannular valve seat on said Valve seat disc surrounding the said otherend of said passage in said valve seat disc, a valve adapted to seat onsaid annular valve seat, a piston slidably mounted in said cylindricalchamber in said element, a stem extending through the passage in saidvalve seat disc connecting said piston to said valve at its inner seatedarea, a coil spring contained in the said axially. extending passage insaid other casing portion operable to exert a seating pressure on saidvalve and a perforated cap adjustably connected to said other casingportion for supporting the outer end of said spring and compressing it.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,916,767 Mason July 4, 1933 2,069,522 Flournoy Feb. 2, 19372,080,824 Kane May 18, 1937 2,506,737 Pacquin May 9, 1950

